Enable correct optimized double modulo operation. (TODO: enable remainder optimization).

runtime/vm/intermediate_language.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 2701 matching lines @@
 
 // Use expected function signatures to help MSVC compiler resolve overloading.
 typedef double (*UnaryMathCFunction) (double x);
 typedef double (*BinaryMathCFunction) (double x, double y);
 
 extern const RuntimeEntry kPowRuntimeEntry(
     "libc_pow", reinterpret_cast<RuntimeFunction>(
         static_cast<BinaryMathCFunction>(&pow)), 0, true);
 
 extern const RuntimeEntry kModRuntimeEntry(
-    "libc_fmod", reinterpret_cast<RuntimeFunction>(
+    "libc_fmod_ieee", reinterpret_cast<RuntimeFunction>(
         static_cast<BinaryMathCFunction>(&fmod)), 0, true);

[Vyacheslav Egorov (Google), 2013/01/30 01:21:21]

How about declaring C function:

double modulo(double left, double right) {
  double remainder = fmod_ieee(left, right);
  if (remainder == 0.0) {
    // We explicitely switch to the positive 0.0 (just in case it was negative).
    remainder = +0.0;
  } else if (remainder < 0) {
    if (right < 0) {
      remainder -= right;
    } else {
      remainder += right;
    }
  }
  return remainder;
}

and use it here and in Double_modulo?

This way we avoid hand written assembly altogether and guarantee that
Double_modulo native and optimized code is in sync. 

[srdjan, 2013/01/30 17:25:07]

Excellent! Done.

On 2013/01/30 01:21:21, Vyacheslav Egorov (Google) wrote:

 
 extern const RuntimeEntry kFloorRuntimeEntry(
     "libc_floor", reinterpret_cast<RuntimeFunction>(
         static_cast<UnaryMathCFunction>(&floor)), 0, true);
 
 extern const RuntimeEntry kCeilRuntimeEntry(
     "libc_ceil", reinterpret_cast<RuntimeFunction>(
         static_cast<UnaryMathCFunction>(&ceil)), 0, true);
 
 extern const RuntimeEntry kTruncRuntimeEntry(
@@ skipping 22 matching lines @@
     default:
       UNREACHABLE();
   }
   return kPowRuntimeEntry;
 }
 
 
 #undef __
 
 }  // namespace dart